Experimental Study on Relative Flow Regime and Broadband Noise of a Propeller Fan

International audienceThe aim of this study is to clarify the relationship between the broadband noise from the low frequency to transition frequency domain generated from the propeller fan and the relative flow regime. In the off design operation condition, the velocity fluctuation having a lower frequency than the blade passing frequency was formed at the leading edge of the blade tip side. The low frequency broadband noise in the off design operation condition has feasibility to generate at the leading edge by adjoined blade interference of the lower frequency than the blade passing frequency. The major factor of the fan noise in the design operation condition was the broadband noise in the transition frequency. From the analysis of CFD, we clarified when the unstable wave due to Karman vortex shedding resonates with the air column resonance frequency made by the blade passage, the pressure fluctuation having a specific frequency is enhanced. These results indicated that the noise in the specific frequency band increased, even though the fan is operated in the design flow rate, when the air column resonance in the blade passage was superimposed to the span direction

プロペラファンの広帯域騒音に関する実験的研究

The present research is a preliminary attempt towards the prediction of the broadband noise from the flow features, compatible with industrial constraints. In the case of low-solidity impeller, the wake rapidly expands in a wide outer part of the blades under the influence of the separation forced by the tip vortex. The broadband noise level in the low-frequency domain became large because the wake vortices with large scale in the low frequency domain were shed from the blade. Since the relative flow of the high-solidity impeller at the maximum efficiency point remains attached over the blades, the strength of vortex-shedding in the wake is reduced. Therefore the broadband noise at the maximum efficiency point is substantially decreased. At the off-design point in low flow rate, the number of blades has limited influence on the flow regime in the wake because separation likely occurs from the leading edge. In this case, the broadband noise increases with the number of blades

Adverse effects of advanced glycation end products on embryonal development

We studied the effects of advanced glycation end products (AGEs), which are known to accumulate in patients with diabetes, autoimmune diseases, or those who smoke, on embryonal development. Pronuclear (PN) embryos were obtained by flushing the fallopian tubes of rats after superovulation and mating. The cleavage rate and blastocyst yield were evaluated at 24, 72, 96, and 120 h of culture. Glyoxal, an AGE-forming aldehyde, suppressed embryonal development at every stage from PN to blastocyst in a concentration-dependent manner. The cleavage rate of the embryo was also signifi cantly decreased by treatment with glyoxal at concentrations of 1 mM or higher. The blastocyst yield was significantly decreased by treatment with glyoxal at concentrations of 0.5 mM or higher. N-acetyl-L-cysteine (L-NAC) at 1 mM significantly suppressed the glyoxal-induced embryonal toxicity. BSA-AGEs at 5 microg/ml or higher concentration signifi cantly reduced the cleavage rate and blastocyst yield compared to those for BSA-treated embryos. L-NAC at 1 mM significantly suppressed BSAAGE-induced embryonal toxicity. Because AGEs are embryo-toxic, AGE contamination may influence the pregnancy rate of in vitro fertilization and embryo transfer. AGEs, which are increased in women under pathological conditions, may also be involved in their infertility.</p

Mechanism Underlying IKK Activation Mediated by the Linear Ubiquitin Chain Assembly Complex (LUBAC)

The linear ubiquitin chain assembly complex (LUBAC) ligase, consisting of HOIL-1L, HOIP, and SHARPIN, specifically generates linear polyubiquitin chains. LUBAC-mediated linear polyubiquitination has been implicated in NF-κB activation. NEMO, a component of the IκB kinase (IKK) complex, is a substrate of LUBAC, but the precise molecular mechanism underlying linear chain-mediated NF-κB activation has not been fully elucidated. Here, we demonstrate that linearly polyubiquitinated NEMO activates IKK more potently than unanchored linear chains. In mutational analyses based on the crystal structure of the complex between the HOIP NZF1 and NEMO CC2-LZ domains, which are involved in the HOIP-NEMO interaction, NEMO mutations that impaired linear ubiquitin recognition activity and prevented recognition by LUBAC synergistically suppressed signal-induced NF-κB activation. HOIP NZF1 bound to NEMO and ubiquitin simultaneously, and HOIP NZF1 mutants defective in interaction with either NEMO or ubiquitin could not restore signal-induced NF-κB activation. Furthermore, linear chain-mediated activation of IKK2 involved homotypic interaction of the IKK2 kinase domain. Collectively, these results demonstrate that linear polyubiquitination of NEMO plays crucial roles in IKK activation and that this modification involves the HOIP NZF1 domain and recognition of NEMO-conjugated linear ubiquitin chains by NEMO on another IKK complex

Prediction of aerodynamic noise in a ring fan based on wake characteristics

A ring fan is a propeller fan that applies an axial-flow impeller with a ring-shaped shroud on the blade tip side. In this study, the entire flow field of the ring fan is simulated using computational fluid dynamics (CFD); the accuracy of the CFD is verified through a comparison with the aerodynamic characteristics of a propeller fan of current model. Moreover, the aerodynamic noise generated by the fan is predicted on the basis of the wake characteristics. The aerodynamic characteristic of the ring fan based on CFD can represent qualitatively the variation in the measured value. The main flow domain of the ring fan is formed at the tip side of the blade because blade tip vortex is not formed at that location. Therefore, the relative velocity of the ring fan is increased by the circumferential velocity. The sound pressure levels of the ring fan within the frequency band of less than 200 Hz are larger than that of the propeller fan. In the analysis of the wake characteristics, it revealed that Karman vortex shedding occurred in the main flow domain in the frequency domain lower than 200 Hz; the aerodynamic noise of the ring fan in the vortex shedding frequency enlarges due to increase in the relative velocity and the velocity fluctuation

Human Exposure to Radiofrequency Energy above 6 GHz: Review of Computational Dosimetry Studies

International guidelines/standards for human protection from electromagnetic fields have been revised recently, especially for frequencies above 6 GHz where new wireless communication systems have been deployed. Above this frequency a new physical quantity "absorbed/epithelia power density" has been adopted as a dose metric. Then, the permissible level of external field strength/power density is derived for practical assessment. In addition, a new physical quantity, fluence or absorbed energy density, is introduced for protection from brief pulses (especially for shorter than 10 sec). These limits were explicitly designed to avoid excessive increases in tissue temperature, based on electromagnetic and thermal modeling studies but supported by experimental data where available. This paper reviews the studies on the computational modeling/dosimetry which are related to the revision of the guidelines/standards. The comparisons with experimental data as well as an analytic solution are also been presented. Future research needs and additional comments on the revision will also be mentioned.Comment: 38 pages, 3 figure

Efficacy and safety of luseogliflozin added to various oral antidiabetic drugs in Japanese patients with type 2 diabetes mellitus

Introduction: Two studies were carried out to investigate the efficacy and safety of luseogliflozin added to existing oral antidiabetic drugs (OADs) in Japanese type 2 diabetic patients inadequately controlled with OAD monotherapy. Materials and Methods: In the trial involving add‐on to sulfonylureas (study 03‐1), patients were randomly assigned to receive luseogliflozin 2.5 mg or a placebo for a 24‐week double‐blind period, followed by a 28‐week open‐label period. In the open‐label trial involving add‐on to other OADs; that is, biguanides, dipeptidyl peptidase‐4 inhibitors, thiazolidinediones, glinides and α‐glucosidase inhibitors (study 03‐2), patients received luseogliflozin for 52 weeks. Results: In study 03‐1, luseogliflozin significantly decreased glycated hemoglobin at the end of the 24‐week double‐blind period compared with the placebo (–0.88%, P < 0.001), and glycated hemoglobin reduction from baseline at week 52 was –0.63%. In study 03‐2, luseogliflozin added to other OADs significantly decreased glycated hemoglobin from baseline at week 52 (–0.52 to –0.68%, P < 0.001 for all OADs). Bodyweight reduction was observed in all add‐on therapies, even with agents associated with weight gain, such as sulfonylureas and thiazolidinediones. Most adverse events were mild in severity. When added to a sulfonylurea, incidences of hypoglycemia during the double‐blind period were 8.7% and 4.2% for luseogliflozin and placebo, respectively, but no major hypoglycemic episodes occurred. The frequency and incidences of adverse events of special interest for sodium glucose cotransporter 2 inhibitors and adverse events associated with combined OADs were acceptable. Conclusions: Add‐on therapies of luseogliflozin to existing OADs improved glycemic control, reduced bodyweight and were well tolerated in Japanese type 2 diabetic patients. These trials were registered with the Japan Pharmaceutical Information Center (add on to sulfonylurea: JapicCTI‐111507; add on to other OADs: JapicCTI‐111508)

Increased Anti-HSP60 and Anti-HSP70 Antibodies in Women with Unexplained Recurrent Pregnancy Loss

　Vascular dysfunction has been reported in women with recurrent pregnancy loss (RPL). We investigated the severity of vascular dysfunction in non-pregnant women with RPL and its correlation with anti-heat shock protein (HSP) antibodies that are known to induce arteriosclerosis. We measured the serum anti-HSP60 antibodies, anti-HSP70 antibodies, and anti-phospholipid antibodies (APA) in 68 women with RPL and 29 healthy controls. Among the women with RPL, 14 had a diagnosis of antiphospholipid syndrome (APS), and in the remaining 54, the causes for RPL were unexplained. Compared to the controls, the brachial-ankle pulse wave velocity (baPWV), carotid augmentation index (cAI), and uterine artery pulsatility index (PI) were all significantly higher in the women with both APS and unexplained RPL. Compared to the controls, the anti-HSP60 antibody levels were significantly higher in the APA-positive group of women with unexplained RPL, and the anti-HSP70 antibody levels were significantly higher in APS and APA-positive group of women with unexplained RPL. However, the anti-HSP60 and anti-HSP70 antibody levels did not correlate with the values of baPWV or cAI. Our results demonstrated anti-HSP60 and anti-HSP70 antibodies are increased in women with unexplained RPL. Further studies are needed to elucidate the roles of anti-HSP antibodies and their pathophysiology in unexplained RPL

Influence of separated vortex on aerodynamic noise of an airfoil blade

In order to clarify the mechanism by which aerodynamic noise is generated from separated flow around an airfoil blade, the relation between the attack angle and the aerodynamic noise of the blade was analyzed using a wind tunnel experiment and a CFD code. In the case of rear surface separation, the separated vortex which has a large-scale structure in the direction of the blade chord is transformed into a structure that concentrates at the trailing edge with an increase in the attack angle. The aerodynamic noise level then becomes small according to the vortex scale in the blade chord. When the flow is separated at the leading edge, a separated vortex of low pressure is formed at the vicinity of the trailing edge. The pressure fluctuations on the blade surface at the vicinity of the trailing edge become large due to the vortex in the wake. It is considered that the aerodynamic noise level increases when the flow is separated at the leading edge because the separated vortex is causing the fluctuations due to wake vortex shedding